Coated paper and process of coating paper



Marh -1 1927.

w. w. M LAURIN COATED PAPER AND PROCESS OF COATING PAPER Filed March 1922 H W m iatentgd Mar. '1, i927.

WILLIAM WALLACE MOLAUBIN, OF BBOOKFIELD, MASEACH U SETTS.

COATED PAPER AND, OI COATING PAPER.

Application filed March 81, 1822. Serial No. 548,317. I

i This invention relates to processes of coating paper and other sheet material, herein for convenience referred to as paper, with an adhesive. The invention is concerned esecially with the rocesses ordinarily reerred to commercially as gummmg paper.

The usual commercial process of umming A umform coating of dry adhesive in granupaper consists, briefly stated, in lszolving the gum in a suitable solvent, usually water, applying a coating of this S0l11t10n tothe surface of the paper and then drying the paper. Sometimes also the coated aper is run between rolls that break up t e continuity of the adhesive coating in order to avoid the tendency of the paper to curl.

The present invention a1m s to lmprove processes of this character with a v1ew to rendering them more econom1cal'and S1111- plifying the equipment necessary perform the gumming or coacting operatlon on a commercial scale. The invention is especlally concerned with the production of a noncurling gummed paper and it involves both a novel product of this character and also a novel process of producmg such paper.

The nature of the invention will be readily understood from the followlng descrlption when read in connection with the accompanying drawings.

The single figure of the drawmgs 1llustrates the steps in the process of coating a web of paper with an adhesive 1n accordance with the present invention.

In the arrangement shown in the drawings the paper to be coated is taken from a roll 2 supported on an axle or spindle which is mounted in suitable trunnions. The first step in the rocess consists in wetting the surface of t e paper that is to be coated, preferably with a liquid in which the gum or adhesive is readily soluble. Since most of the gummed papers are coated with an adhesive that is soluble in water this liquid is usually employed in wetting the web of paper. The wetting operation inthe arrangement shown is performed by running the web 3 between up er and lower rolls 4 and 5, respectively, 0 a wetting apparatus of a common form, the roll 5 runnin in contact with another roll 6 that dips mto a body of water held in a tank or vessel 7. This apparatus wets the lower surface of the web 3 uniforml as the web is advanced between the rolls. The lower wetted surface of the web becomes uppermost upon leaving the roll 4, and the web next travels under a shaking box 8 having a screen in the bottom thereof and contalning a supply of the gum 9 which is to be applied to the paper. This adhesive is in a pulverized or powdered condition and it is sprinkled on the underneath the box 8. A substantially lar form thus is applied to the web. Inasmuch as the adheslve is soluble in the liquid with which the web is wet, it is united to the web through its own adhesion.

The web, now coated, is next dried, and for this pur ose it is passed over a heated drum 10 which is rotated slowly so that the drying operation is substantially completed by the time the web leaves the surface of the drum. The coated Web next passes between upper and lower rolls 11 and 12,'re-

.lfipper surface of the paper as the web is spectively, which roll the adhesive into the surface of the paper, smooth the coated surface, and make the coated sheet substantially uniform in thickness From these rolls the web passes to a winding spindle 14 which is rotated by any convenient mechanism and acts to wind up the web of paper into the form of a roll again The drag exerted on the paper by the winding spindle 14 and the drum 10 feeds the .web through the other mechanisms above described althou h the rolls 4, 5, 1 1 and 12 may also be driven if desired It will now be appreciated that this process of gummingpaperis more economical than prior processes since it saves the expense of dissolving the gum and since it materially reduces the amount of heat required in drying, the uantity of water that must be evaporated rom a given area of paper being substantially less in this process than in prior processes The e uipment required also is simpler and the di culties commonly experienced inhandling the gum in a liquid condition are avoided The gummed sheet produced by this process has no tendency to curl since the coating of gum thereon is in a powdered or granular condition and is, therefore, discontinuous Having thus described my invention, what I desire to claim as new is:

1. That improvement in the process of coating paper with an adhesive which -consists in wetting the surface of the aper to be coated, and then applying to said surface a coating of powdered adhesive soluble in the liquid with which the surface is wet and then drying the paper. g

2. That improvement in the process of coating paper with an adhesive which consists in wetting with water the surface of the paper to be coated, then applying to said surface a coating of powdered adhesive soluble in water, and then drying the paper so coated.

3. That improvement in the process of coating paper with an adhesive which consists in wetting the surface of the paper to be coated, then applying a coating of powdered adhesive to said surface while the surface is still wet, drying the paper, and pressing said adhesive into the surface of the paper.

4. That improvement in the process of coating paper with an adhesive which consists in wetting the surface of the paper to be coated, then applying a coating of powdered adhesive to said surface while the surface is still wet, and subsequently rolling said adhesive into the surface of the paper.

5. That improvement in the process of coating paper with an adhesive which consists in wetting the surface of the pa er to be coated, then applying a coating 0 powdered adhesive to said surface while the surface is still wet, and then drying the coated sheet and rolling the adhesive into the surface of said sheet.

6. That improvement in the process of coating aper with an adhesive which consists in eeding a continuous web of paper, applying a liquid to the surface of said web at a given point in its path of travel and thereby wetting the surface of the paper, applying to the surface so wet a coating of powdered adhesive soluble in said liquid, and then drying the coated web of paper.

7. That improvement in the process of coating paper with an adhesive which consists in feeding a continuous web of paper,

applying a liquid to the surface of said web.

at a given point in its path of travel and thereby wettin the surface of the paper, sprinkling on t e wet surface of the paper a coating of a powdered adhesive soluble in said liquid, drying the coated web, and smoothing the coating so applied to the web. 8. An article of the character described comprising a sheet of paper having a substantially uniform discontinuous coating of granular gum united to the paper through the adhesion of the grains of the gum to the surface of the paper.

WILLIAM WALLACE MGLAURIN. 

